This cartoon was recently posted on Facebook. My sister (who is a retired HS English teacher) says the grammar is wrong and that the correct wording should be: "Neither one of us is." but I disagree.
I am not an English teacher but I believe that "US" relates to "WE" and the correct wording for that pronoun is "WE ARE". On the other hand "ONE OF US" relates to "I" and "YOU" but the correct wording for those pronouns would be "I AM" or "YOU ARE" ... There absolutely is no place in English where we correctly use "I IS", "YOU IS", or "WE IS" so why would "US IS" be correct?